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Proceedings Paper

A 4mm spectroscopic dual-beam receiver for the Robert C. Byrd green bank radio telescope
Author(s): Steven White; David Frayer; Mike Stennes; Robert Simon; Galen Watts; Roger Norrod; Eric Bryerton; Sivasankaran Srikanth; Marian Pospieszalski
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Paper Abstract

With a 100-meter aperture, and recent improvements to its surface accuracy and servo system upgrades, the Robert C. Byrd Green Bank Telescope is the most sensitive telescope operating at 90 GHz. A dual-feed heterodyne receiver is developed for observations at the lower frequency end of the 3-4mm atmospheric window (67 to 93 GHz). The science goals are primarily molecular spectroscopic studies of star formation and astrochemistry both internal and external to the Milky Way galaxy. Studies of the structural and physical properties of star-forming, cold-cloud cores will be revolutionized with molecular spectroscopy of the deuterium and other important species within the band. Essential for spectroscopy is the ability to remove slow gain and atmospheric variations. An optical table external to the cooled components rotates into the path of either beam an ambient temperature load, an offset mirror for viewing an internal cold load, or a quarter-wave plate that produces circular polarization for VLBI observations. A composite waveguide window comprised of HDPE, Zitex, and z-cut quartz provides a high-strength, low-loss medium for transmission of the signal to the cooled corrugated feed horn. An orthomode transducer separates the polarization components which are amplified by low noise HEMT amplifiers. Warm W-band MMIC amplifiers are required to compensate a negative gain slope and to reduce noise contributions from the down conversion to the GBT IF frequencies. Initial science results and receiver performance during commissioning observations will be presented along with details of the component design.

Paper Details

Date Published: 24 September 2012
PDF: 9 pages
Proc. SPIE 8452, Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI, 84522J (24 September 2012); doi: 10.1117/12.924122
Show Author Affiliations
Steven White, National Radio Astronomy Observatory (United States)
David Frayer, National Radio Astronomy Observatory (United States)
Mike Stennes, National Radio Astronomy Observatory (United States)
Robert Simon, National Radio Astronomy Observatory (United States)
Galen Watts, National Radio Astronomy Observatory (United States)
Roger Norrod, National Radio Astronomy Observatory (United States)
Eric Bryerton, National Radio Astronomy Observatory (United States)
Sivasankaran Srikanth, National Radio Astronomy Observatory (United States)
Marian Pospieszalski, National Radio Astronomy Observatory (United States)


Published in SPIE Proceedings Vol. 8452:
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy VI
Wayne S. Holland, Editor(s)

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